Four groups of reinforced recycled concrete beams were prefabricated, whose replacement rate of recycled coarse aggregates were 0%, 40%, 70% and 100%, respectively. According to the theoretical strengthening quantity of prestressed CFRP sheets between tensile failure and debonding failure mode, one beam of each group under pre-cracking was strengthened with a layer of prestressed CFRP sheets, while the other one was strengthened with two layers of sheets. Next, experimental study on flexural capacity of all beams was conducted. The test results show that with the increase of prestressed CFRP sheets, the flexural capacity of the strengthened beams increases, while the number and width of transverse cracks in the tensile zone of the beams increases and decreases when the beams yield, respectively. The flexural capacity of the strengthened beams decreases with the replacement rate of recycled coarse aggregates. When the beams yield the number and the width of transverse cracks in the tensile zone decreases and increases, respectively. Finally, based on test results and plane section assumption, design formulas are proposed to calculate the flexural capacity of reinforced recycled concrete beams strengthened with prestressed CFRP sheets. In the formulae, the effects of replacement rate of recycled coarse aggregates and the secondary loads of the strengthened beams are considered. The calculation results agree well with the test results, which indicates that the proposed formulas can provide good reference for design of reinforced recycled concrete beams strengthened with prestressed CFRP sheets.